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Castiglioni VG, Olmo-Uceda MJ, Martín S, Félix MA, González R, Elena SF. Experimental evolution of an RNA virus in Caenorhabditis elegans. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2024; 123:105623. [PMID: 38901623 DOI: 10.1016/j.meegid.2024.105623] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 06/02/2024] [Accepted: 06/17/2024] [Indexed: 06/22/2024]
Abstract
The discovery of Orsay virus (OrV), the first virus infecting wild populations of Caenorhabditis elegans, has boosted studies of viral immunity pathways in this nematode. Considering the many advantages that C. elegans offers for fundamental research in host-pathogen interactions, this pathosystem has high potential to become a model system for experimental virus evolution studies. However, the evolutionary constraints - i.e, the balance between genetic variation, selection, drift and historical contingency- operating in this pathosystem have barely been explored. Here we describe for the first time an evolution experiment of two different OrV strains in C. elegans. Comparison of the two ancestral strains showed differences in infectivity and sequence, and highlighted the importance of consistently normalize viral inocula for meaningful comparisons among strains. After 10 serial passages of evolution, we report slight changes in infectivity and non-synonymous mutations fixed in the evolved viral populations. In addition, we observed numerous minor variants emerging in the viral population. These minor variants were not randomly distributed along the genome but concentrated in polymorphic genomic regions. Overall, our work established the grounds for future experimental virus evolution studies using Caenorhabditis nematodes.
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Affiliation(s)
- Victoria G Castiglioni
- Instituto de Biología Integrativa de Sistemas (CSIC-Universitat de València), Paterna, 46980 València, Spain
| | - María J Olmo-Uceda
- Instituto de Biología Integrativa de Sistemas (CSIC-Universitat de València), Paterna, 46980 València, Spain
| | - Susana Martín
- Instituto de Biología Integrativa de Sistemas (CSIC-Universitat de València), Paterna, 46980 València, Spain
| | - Marie-Anne Félix
- Institut de Biologie de l'École Normale Supérieure, CNRS, INSERM, 75005 Paris, France
| | - Rubén González
- Instituto de Biología Integrativa de Sistemas (CSIC-Universitat de València), Paterna, 46980 València, Spain; Institut de Biologie de l'École Normale Supérieure, CNRS, INSERM, 75005 Paris, France.
| | - Santiago F Elena
- Instituto de Biología Integrativa de Sistemas (CSIC-Universitat de València), Paterna, 46980 València, Spain; Santa Fe Institute, Sant Fe, NM 87501, USA.
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2
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Caldwell HS, Kuo L, Pata JD, Dupuis AP, Arnold JJ, Yeager C, Stout J, Koetzner CA, Payne AF, Bialosuknia SM, Banker EM, Nolen TA, Cameron CE, Ciota AT. Maintenance of a host-specific minority mutation in the West Nile virus NS3. iScience 2023; 26:107468. [PMID: 37593454 PMCID: PMC10428113 DOI: 10.1016/j.isci.2023.107468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Revised: 06/22/2023] [Accepted: 07/21/2023] [Indexed: 08/19/2023] Open
Abstract
West Nile virus (WNV), the most prevalent arthropod-borne virus (arbovirus) in the United States, is maintained in a cycle between Culex spp. mosquitoes and birds. Arboviruses exist within hosts and vectors as a diverse set of closely related genotypes. In theory, this genetic diversity can facilitate adaptation to distinct environments during host cycling, yet host-specific fitness of minority genotypes has not been assessed. Utilizing WNV deep-sequencing data, we previously identified a naturally occurring, mosquito-biased substitution, NS3 P319L. Using both cell culture and experimental infection in natural hosts, we demonstrated that this substitution confers attenuation in vertebrate hosts and increased transmissibility by mosquitoes. Biochemical assays demonstrated temperature-sensitive ATPase activity consistent with host-specific phenotypes. Together these data confirm the maintenance of host-specific minority variants in arbovirus mutant swarms, suggest a unique role for NS3 in viral fitness, and demonstrate that intrahost sequence data can inform mechanisms of host-specific adaptation.
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Affiliation(s)
- Haley S. Caldwell
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA
| | - Lili Kuo
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Janice D. Pata
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA
- Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Alan P. Dupuis
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Jamie J. Arnold
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Calvin Yeager
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Jessica Stout
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Cheri A. Koetzner
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Anne F. Payne
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Sean M. Bialosuknia
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Elyse M. Banker
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Taylor A. Nolen
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
| | - Craig E. Cameron
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Alexander T. Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA
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3
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Talmi-Frank D, Byas AD, Murrieta R, Weger-Lucarelli J, Rückert C, Gallichotte EN, Yoshimoto JA, Allen C, Bosco-Lauth AM, Graham B, Felix TA, Brault AC, Ebel GD. Intracellular Diversity of WNV within Circulating Avian Peripheral Blood Mononuclear Cells Reveals Host-Dependent Patterns of Polyinfection. Pathogens 2023; 12:767. [PMID: 37375457 DOI: 10.3390/pathogens12060767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Revised: 05/12/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
Arthropod-borne virus (arbovirus) populations exist as mutant swarms that are maintained between arthropods and vertebrates. West Nile virus (WNV) population dynamics are host-dependent. In American crows, purifying selection is weak and population diversity is high compared to American robins, which have 100- to 1000-fold lower viremia. WNV passed in robins leads to fitness gains, whereas that passed in crows does not. Therefore, we tested the hypothesis that high crow viremia allows for higher genetic diversity within individual avian peripheral blood mononuclear cells (PBMCs), reasoning that this could have produced the previously observed host-specific differences in genetic diversity and fitness. Specifically, we infected cells and birds with a molecularly barcoded WNV and sequenced viral RNA from single cells to quantify the number of WNV barcodes in each. Our results demonstrate that the richness of WNV populations within crows far exceeds that in robins. Similarly, rare WNV variants were maintained by crows more frequently than by robins. Our results suggest that increased viremia in crows relative to robins leads to the maintenance of defective genomes and less prevalent variants, presumably through complementation. Our findings further suggest that weaker purifying selection in highly susceptible crows is attributable to this higher viremia, polyinfections and complementation.
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Affiliation(s)
- Dalit Talmi-Frank
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Alex D Byas
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Reyes Murrieta
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - James Weger-Lucarelli
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Claudia Rückert
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, NV 89557, USA
| | - Emily N Gallichotte
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Janna A Yoshimoto
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Chris Allen
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Angela M Bosco-Lauth
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Barbara Graham
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
| | - Todd A Felix
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Lakewood, CO 80228, USA
| | - Aaron C Brault
- Division of Vector-Borne Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Fort Collins, CO 80521, USA
| | - Gregory D Ebel
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
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4
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Sun B, Ni M, Liu H, Liu D. Viral intra-host evolutionary dynamics revealed via serial passage of Japanese encephalitis virus in vitro. Virus Evol 2023; 9:veac103. [PMID: 37205166 PMCID: PMC10185921 DOI: 10.1093/ve/veac103] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 10/04/2022] [Accepted: 03/21/2023] [Indexed: 12/02/2023] Open
Abstract
Analyses of viral inter- and intra-host mutations could better guide the prevention and control of infectious diseases. For a long time, studies on viral evolution have focused on viral inter-host variations. Next-generation sequencing has accelerated the investigations of viral intra-host diversity. However, the theoretical basis and dynamic characteristics of viral intra-host mutations remain unknown. Here, using serial passages of the SA14-14-2 vaccine strain of Japanese encephalitis virus (JEV) as the in vitro model, the distribution characteristics of 1,788 detected intra-host single-nucleotide variations (iSNVs) and their mutated frequencies from 477 deep-sequenced samples were analyzed. Our results revealed that in adaptive (baby hamster kidney (BHK)) cells, JEV is under a nearly neutral selection pressure, and both non-synonymous and synonymous mutations represent an S-shaped growth trend over time. A higher positive selection pressure was observed in the nonadaptive (C6/36) cells, and logarithmic growth in non-synonymous iSNVs and linear growth in synonymous iSNVs were observed over time. Moreover, the mutation rates of the NS4B protein and the untranslated region (UTR) of the JEV are significantly different between BHK and C6/36 cells, suggesting that viral selection pressure is regulated by different cellular environments. In addition, no significant difference was detected in the distribution of mutated frequencies of iSNVs between BHK and C6/36 cells.
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Affiliation(s)
- Bangyao Sun
- School of Medical Laboratory, Weifang Medical University, Baotong West Street, Weifang 261053, China
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Xiaohongshan 44#, Wuhan 430000, China
- Computational Virology Group, Center for Bacteria and Viruses Resources and Bioinformation, Wuhan Institute of Virology, Chinese Academy of Sciences, Xiaohongshan 44#, Wuhan 430000, China
- University of Chinese Academy of Sciences, Yuquan Road 19#, Beijing 100049, China
| | - Ming Ni
- Beijing Institute of Radiation Medicine, Taiping Road 27#, Beijing 100850, China
| | - Haizhou Liu
- Computational Virology Group, Center for Bacteria and Viruses Resources and Bioinformation, Wuhan Institute of Virology, Chinese Academy of Sciences, Xiaohongshan 44#, Wuhan 430000, China
| | - Di Liu
- CAS Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Chinese Academy of Sciences, Xiaohongshan 44#, Wuhan 430000, China
- Computational Virology Group, Center for Bacteria and Viruses Resources and Bioinformation, Wuhan Institute of Virology, Chinese Academy of Sciences, Xiaohongshan 44#, Wuhan 430000, China
- University of Chinese Academy of Sciences, Yuquan Road 19#, Beijing 100049, China
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5
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Frank DT, Byas AD, Murrieta R, Weger-Lucarelli J, Rückert C, Gallichotte E, Yoshimoto JA, Allen C, Bosco-Lauth AM, Graham B, Felix TA, Brault A, Ebel GD. Intracellular diversity of WNV within circulating avian peripheral blood mononuclear cells reveals host-dependent patterns of polyinfection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.27.525959. [PMID: 36747638 PMCID: PMC9900929 DOI: 10.1101/2023.01.27.525959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Error-prone replication of RNA viruses generates the genetic diversity required for adaptation within rapidly changing environments. Thus, arthropod-borne virus (arbovirus) populations exist in nature as mutant swarms that are maintained between arthropods and vertebrates. Previous studies have demonstrated that West Nile virus (WNV) population dynamics are host dependent: In American crows, which experience extremely high viremia, purifying selection is weak and population diversity is high compared to American robins, which have 100 to 1000-fold lower viremia. WNV passed in robins experiences fitness gains, whereas that passed in crows does not. Therefore, we tested the hypothesis that high crow viremia allows higher genetic diversity within individual avian peripheral-blood mononuclear cells (PBMCs), reasoning that this could have produced the previously observed host-specific differences in genetic diversity and fitness. Specifically, we infected cells and birds with a novel, barcoded version of WNV and sequenced viral RNA from single cells to quantify the number of WNV barcodes that each contained. Our results demonstrate that the richness of WNV populations within crows far exceeds that in robins. Similarly, rare WNV variants were maintained by crows more frequently than by robins. Our results suggest that increased viremia in crows relative to robins leads to maintenance of defective genomes and less prevalent variants, presumably through complementation. Our findings further suggest that weaker purifying selection in highly susceptible crows is attributable to this higher viremia, polyinfections and complementation. These studies further document the role of particular, ecologically relevant hosts in shaping virus population structure. Author Summary WNV mutational diversity in vertebrates is species-dependent. In crows, low frequency variants are common, and viral populations are more diverse. In robins, fewer mutations become permanent fixtures of the overall viral population. We infected crows, robins and a chicken cell line with a genetically marked (barcoded) WNV. Higher levels of virus led to multiple unique WNV genomes infecting individual cells, even when a genotype was present at low levels in the input viral stock. Our findings suggest that higher levels of circulating virus in natural hosts allow less fit viruses to survive in RNA virus populations through complementation by more fit viruses. This is significant as it allows less represented and less fit viruses to be maintained at low levels until they potentially emerge when virus environments change. Overall our data reveal new insights on the relationships between host susceptibility to high viremia and virus evolution.
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Affiliation(s)
- Dalit Talmi Frank
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Alex D. Byas
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Reyes Murrieta
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - James Weger-Lucarelli
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Claudia Rückert
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, Nevada, USA
| | - Emily Gallichotte
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Janna A. Yoshimoto
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Chris Allen
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Angela M. Bosco-Lauth
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Barbara Graham
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
| | - Todd A. Felix
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Golden, CO, USA
| | - Aaron Brault
- Division of Vector-borne Diseases, National Center for Emerging Zoonotic Infectious Diseases, Centers for Disease Control and Prevention Fort Collins, Colorado, USA
| | - Gregory D. Ebel
- Center for Vector-borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, USA
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6
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Caldwell HS, Pata JD, Ciota AT. The Role of the Flavivirus Replicase in Viral Diversity and Adaptation. Viruses 2022; 14:1076. [PMID: 35632818 PMCID: PMC9143365 DOI: 10.3390/v14051076] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/03/2022] [Accepted: 05/06/2022] [Indexed: 02/04/2023] Open
Abstract
Flaviviruses include several emerging and re-emerging arboviruses which cause millions of infections each year. Although relatively well-studied, much remains unknown regarding the mechanisms and means by which these viruses readily alternate and adapt to different hosts and environments. Here, we review a subset of the different aspects of flaviviral biology which impact host switching and viral fitness. These include the mechanism of replication and structural biology of the NS3 and NS5 proteins, which reproduce the viral genome; rates of mutation resulting from this replication and the role of mutational frequency in viral fitness; and the theory of quasispecies evolution and how it contributes to our understanding of genetic and phenotypic plasticity.
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Affiliation(s)
- Haley S. Caldwell
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA;
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
| | - Janice D. Pata
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
- Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
| | - Alexander T. Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY 12159, USA;
- Department of Biomedical Sciences, State University of New York at Albany, School of Public Health, Rensselaer, NY 12144, USA;
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7
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Abstract
6 years ago, I published a Cell Host and Microbe paper that described randomization of virus genetic populations during mosquito infection. From within the evolutionary chaos, however, there is an order that can reveal a virus' past. Using these insights, I forged a career harnessing virus evolution to understand epidemiological patterns.
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8
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Byas AD, Gallichotte EN, Hartwig AE, Porter SM, Gordy PW, Felix TA, Bowen RA, Ebel GD, Bosco-Lauth AM. American alligators are capable of West Nile virus amplification, mosquito infection and transmission. Virology 2022; 568:49-55. [PMID: 35114499 PMCID: PMC8866202 DOI: 10.1016/j.virol.2022.01.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
West Nile virus (WNV) overwintering is poorly understood and likely multifactorial. Interest in alligators as a potential amplifying host arose when it was shown that they develop viremias theoretically sufficient to infect mosquitoes. We examined potential ways in which alligators may contribute to the natural ecology of WNV. We experimentally demonstrated that alligators are capable of WNV amplification with subsequent mosquito infection and transmission capability, that WNV-infected mosquitoes readily infect alligators and that water can serve as a source of infection for alligators but does not easily serve as in intermediate means for transmission between birds and alligators. These findings indicate potential mechanisms for maintenance of WNV outside of the primary bird-mosquito transmission cycle.
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Affiliation(s)
- Alex D. Byas
- Colorado State University, Microbiology, Immunology & Pathology Department, Fort Collins, CO, USA
| | - Emily N. Gallichotte
- Colorado State University, Microbiology, Immunology & Pathology Department, Fort Collins, CO, USA
| | - Airn E. Hartwig
- Colorado State University, Biomedical Sciences Department, Fort Collins, CO, USA
| | - Stephanie M. Porter
- Colorado State University, Microbiology, Immunology & Pathology Department, Fort Collins, CO, USA
| | - Paul W. Gordy
- Colorado State University, Biomedical Sciences Department, Fort Collins, CO, USA
| | - Todd A. Felix
- United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, Lakewood, CO, USA
| | - Richard A. Bowen
- Colorado State University, Biomedical Sciences Department, Fort Collins, CO, USA
| | - Gregory D. Ebel
- Colorado State University, Microbiology, Immunology & Pathology Department, Fort Collins, CO, USA
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9
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Murrieta RA, Garcia-Luna SM, Murrieta DJ, Halladay G, Young MC, Fauver JR, Gendernalik A, Weger-Lucarelli J, Rückert C, Ebel GD. Impact of extrinsic incubation temperature on natural selection during Zika virus infection of Aedes aegypti and Aedes albopictus. PLoS Pathog 2021; 17:e1009433. [PMID: 34752502 PMCID: PMC8629396 DOI: 10.1371/journal.ppat.1009433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 11/29/2021] [Accepted: 10/18/2021] [Indexed: 01/10/2023] Open
Abstract
Arthropod-borne viruses (arboviruses) require replication across a wide range of temperatures to perpetuate. While vertebrate hosts tend to maintain temperatures of approximately 37°C—40°C, arthropods are subject to ambient temperatures which can have a daily fluctuation of > 10°C. Temperatures impact vector competence, extrinsic incubation period, and mosquito survival unimodally, with optimal conditions occurring at some intermediate temperature. In addition, the mean and range of daily temperature fluctuations influence arbovirus perpetuation and vector competence. The impact of temperature on arbovirus genetic diversity during systemic mosquito infection, however, is poorly understood. Therefore, we determined how constant extrinsic incubation temperatures of 25°C, 28°C, 32°C, and 35°C control Zika virus (ZIKV) vector competence and population dynamics within Aedes aegypti and Aedes albopictus mosquitoes. We also examined fluctuating temperatures which better mimic field conditions in the tropics. We found that vector competence varied in a unimodal manner for constant temperatures peaking between 28°C and 32°C for both Aedes species. Transmission peaked at 10 days post-infection for Aedes aegypti and 14 days for Aedes albopictus. Conversely, fluctuating temperature decreased vector competence. Using RNA-seq to characterize ZIKV population structure, we identified that temperature alters the selective environment in unexpected ways. During mosquito infection, constant temperatures more often elicited positive selection whereas fluctuating temperatures led to strong purifying selection in both Aedes species. These findings demonstrate that temperature has multiple impacts on ZIKV biology, including major effects on the selective environment within mosquitoes. Arthropod-borne viruses (arboviruses) have emerged in recent decades due to complex factors that include increases in international travel and trade, the breakdown of public health infrastructure, land use changes, and many others. Climate change also has the potential to shift the geographical ranges of arthropod vectors, consequently increasing the global risk of arbovirus infection. Changing temperatures may alter the virus-host interaction, ultimately resulting in the emergence of new viruses and virus genotypes in new areas. Therefore, we sought to characterize how temperature (both constant and fluctuating) alters the ability of Aedes aegypti and Aedes albopictus to transmit Zika virus, and how it influences virus populations within mosquitoes. We found that intermediate temperatures maximize virus transmission compared to more extreme and fluctuating temperatures. Constant temperatures increased positive selection on virus genomes, while fluctuating temperatures strengthened purifying selection. Our studies provide evidence that in addition to altering vector competence, temperature significantly influences natural selection within mosquitoes.
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Affiliation(s)
- Reyes A. Murrieta
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Selene M. Garcia-Luna
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
| | - Deedra J. Murrieta
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Gareth Halladay
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Michael C. Young
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - Joseph R. Fauver
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- Yale School of Public Health, Department of Epidemiology of Microbial Diseases, Laboratory of Epidemiology of Public Health, New Haven, Connecticut, United States of America
| | - Alex Gendernalik
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
| | - James Weger-Lucarelli
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- Department of Biomedical Sciences & Pathobiology, Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Claudia Rückert
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- Department of Biochemistry and Molecular Biology, College of Agriculture, Biotechnology & Natural Resources, University of Nevada, Reno, Nevada, United States of America
| | - Gregory D. Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado, United States of America
- * E-mail:
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10
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Talavera-Aguilar LG, Murrieta RA, Kiem S, Cetina-Trejo RC, Baak-Baak CM, Ebel GD, Blitvich BJ, Machain-Williams C. Infection, dissemination, and transmission efficiencies of Zika virus in Aedes aegypti after serial passage in mosquito or mammalian cell lines or alternating passage in both cell types. Parasit Vectors 2021; 14:261. [PMID: 34006306 PMCID: PMC8130322 DOI: 10.1186/s13071-021-04726-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/16/2021] [Indexed: 11/10/2022] Open
Abstract
Background Zika virus (ZIKV) is an arthropod-borne virus (arbovirus) with an urban transmission cycle that primarily involves humans and Aedes aegypti. Evidence suggests that the evolution of some arboviruses is constrained by their dependency on alternating between disparate (vertebrate and invertebrate) hosts. The goals of this study are to compare the genetic changes that occur in ZIKV after serial passaging in mosquito or vertebrate cell lines or alternate passaging in both cell types and to compare the replication, dissemination, and transmission efficiencies of the cell culture-derived viruses in Ae. aegypti. Methods An isolate of ZIKV originally acquired from a febrile patient in Yucatan, Mexico, was serially passaged six times in African green monkey kidney (Vero) cells or Aedes albopictus (C6/36) cells or both cell types by alternating passage. A colony of Ae. aegypti from Yucatan was established, and mosquitoes were challenged with the cell-adapted viruses. Midguts, Malpighian tubules, ovaries, salivary glands, wings/legs and saliva were collected at various times after challenge and tested for evidence of virus infection. Results Genome sequencing revealed the presence of two non-synonymous substitutions in the premembrane and NS1 regions of the mosquito cell-adapted virus and two non-synonymous substitutions in the capsid and NS2A regions of both the vertebrate cell-adapted and alternate-passaged viruses. Additional genetic changes were identified by intrahost variant frequency analysis. Virus maintained by continuous C6/36 cell passage was significantly more infectious in Ae. aegypti than viruses maintained by alternating passage and consecutive Vero cell passage. Conclusions Mosquito cell-adapted ZIKV displayed greater in vivo fitness in Ae. aegypti compared to the other viruses, indicating that obligate cycling between disparate hosts carries a fitness cost. These data increase our understanding of the factors that drive ZIKV adaptation and evolution and underscore the important need to consider the in vivo passage histories of flaviviruses to be evaluated in vector competence studies. Graphical abstract ![]()
Supplementary Information The online version contains supplementary material available at 10.1186/s13071-021-04726-1.
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Affiliation(s)
- Lourdes G Talavera-Aguilar
- Laboratorio de Arbovirología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, México
| | - Reyes A Murrieta
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Sungmin Kiem
- Department of Infectious Diseases in Internal Medicine, Sejong Chungnam National University Hospital, School of Medicine, Chungnam National University, Sejong, Korea
| | - Rosa C Cetina-Trejo
- Laboratorio de Arbovirología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, México
| | - Carlos M Baak-Baak
- Laboratorio de Arbovirología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, México
| | - Gregory D Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO, USA
| | - Bradley J Blitvich
- Department of Veterinary Microbiology and Preventive Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Carlos Machain-Williams
- Laboratorio de Arbovirología, Centro de Investigaciones Regionales "Dr. Hideyo Noguchi", Universidad Autónoma de Yucatán, Mérida, México.
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11
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Intra-host evolutionary dynamics of the hepatitis C virus among people who inject drugs. Sci Rep 2021; 11:9986. [PMID: 33976241 PMCID: PMC8113533 DOI: 10.1038/s41598-021-88132-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 03/31/2021] [Indexed: 02/03/2023] Open
Abstract
Most individuals chronically infected with hepatitis C virus (HCV) are asymptomatic during the initial stages of infection and therefore the precise timing of infection is often unknown. Retrospective estimation of infection duration would improve existing surveillance data and help guide treatment. While intra-host viral diversity quantifications such as Shannon entropy have previously been utilized for estimating duration of infection, these studies characterize the viral population from only a relatively short segment of the HCV genome. In this study intra-host diversities were examined across the HCV genome in order to identify the region most reflective of time and the degree to which these estimates are influenced by high-risk activities including those associated with HCV acquisition. Shannon diversities were calculated for all regions of HCV from 78 longitudinally sampled individuals with known seroconversion timeframes. While the region of the HCV genome most accurately reflecting time resided within the NS3 gene, the gene region with the highest capacity to differentiate acute from chronic infections was identified within the NS5b region. Multivariate models predicting duration of infection from viral diversity significantly improved upon incorporation of variables associated with recent public, unsupervised drug use. These results could assist the development of strategic population treatment guidelines for high-risk individuals infected with HCV and offer insights into variables associated with a likelihood of transmission.
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12
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Pontremoli C, Forni D, Clerici M, Cagliani R, Sironi M. Alternation between taxonomically divergent hosts is not the major determinant of flavivirus evolution. Virus Evol 2021; 7:veab040. [PMID: 33976907 PMCID: PMC8093920 DOI: 10.1093/ve/veab040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Flaviviruses display diverse epidemiological and ecological features. Tick-borne and mosquito-borne flaviviruses (TBFV and MBFV, respectively) are important human pathogens that alternate replication in invertebrate vectors and vertebrate hosts. The Flavivirus genus also includes insect-specific viruses (ISFVs) and viruses with unknown invertebrate hosts. It is generally accepted that viruses that alternate between taxonomically different hosts evolve slowly and that the evolution of MBFVs and TBFVs is dominated by strong constraints, with limited episodes of positive selection. We exploited the availability of flavivirus genomes to test these hypotheses and to compare their rates and patterns of evolution. We estimated the substitution rates of CFAV and CxFV (two ISFVs) and, by taking into account the time-frame of measurement, compared them with those of other flaviviruses. Results indicated that CFAV and CxFV display relatively different substitution rates. However, these data, together with estimates for single-host members of the Flaviviridae family, indicated that MBFVs do not display relatively slower evolution. Conversely, TBFVs displayed some of lowest substitution rates among flaviviruses. Analysis of selective patterns over longer evolutionary time-frames confirmed that MBFVs evolve under strong purifying selection. Interestingly, TBFVs and ISFVs did not show extremely different levels of constraint, although TBFVs alternate among hosts, whereas ISFVs do not. Additional results showed that episodic positive selection drove the evolution of MBFVs, despite their high constraint. Positive selection was also detected on two branches of the TBFVs phylogeny that define the seabird clade. Thus, positive selection was much more common during the evolution of arthropod-borne flaviviruses than previously thought. Overall, our data indicate that flavivirus evolutionary patterns are complex and most likely determined by multiple factors, not limited to the alternation between taxonomically divergent hosts. The frequency of both positive and purifying selection, especially in MBFVs, suggests that a minority of sites in the viral polyprotein experience weak constraint and can evolve to generate new viral phenotypes and possibly promote adaptation to new hosts.
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Affiliation(s)
| | - Diego Forni
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini 23842, Italy
| | - Mario Clerici
- Department of Physiopathology and Transplantation, University of Milan, Milan 20122, Italy,Don C. Gnocchi Foundation ONLUS, IRCCS, Milan 20121, Italy
| | - Rachele Cagliani
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini 23842, Italy
| | - Manuela Sironi
- Scientific Institute IRCCS E. MEDEA, Bioinformatics, Bosisio Parini 23842, Italy
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13
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Genome Number and Size Polymorphism in Zika Virus Infectious Units. J Virol 2021; 95:JVI.00787-20. [PMID: 33328311 PMCID: PMC8094933 DOI: 10.1128/jvi.00787-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Accepted: 12/04/2020] [Indexed: 12/18/2022] Open
Abstract
The arthropod-borne Zika virus (ZIKV) infects humans and can cause severe neurological sequelae, particularly in fetuses infected in utero. How this virus has been able to spread across vast geological ranges and evolve in new host populations is not yet understood. Zika virus (ZIKV; Flaviviridae, Flavivirus) is an arthropod-borne infection that can result in severe outcomes, particularly in fetuses infected in utero. It has been assumed that infection by ZIKV, as well as other viruses, is largely initiated by individual virus particles binding to and entering a cell. However, recent studies have demonstrated that multiple virus particles are frequently delivered to a cell simultaneously and that this collective particle delivery enhances infection. ZIKV is maintained in nature between Aedes aegypti mosquitos and vertebrate hosts, including humans. Human infection is initiated through the injection of a relatively small initial inoculum comprised of a genetically complex virus population. Since most mutations decrease virus fitness, collective particle transmission could benefit ZIKV and other arthropod-borne diseases by facilitating the maintenance of genetic complexity and adaptability during infection or through other mechanisms. Therefore, we utilized a barcoded ZIKV to quantify the number of virus genomes that initiate a plaque. We found that individual plaques contain a mean of 10 infecting viral genomes (range, 1 to 212). Few plaques contained more than two dominant genomes. To determine whether multigenome infectious units consist of collectively transmitting virions, infectious units of ZIKV were then separated mechanically by centrifugation, and heavier fractions were found to contain more genomes per plaque-forming unit, with larger diameters. Finally, larger/heavier infectious units reformed after removal. These data suggest that ZIKV populations consist of a variety of infectious unit sizes, likely mostly made up of aggregates, and only rarely begin with a single virus genome. IMPORTANCE The arthropod-borne Zika virus (ZIKV) infects humans and can cause severe neurological sequelae, particularly in fetuses infected in utero. How this virus has been able to spread across vast geological ranges and evolve in new host populations is not yet understood. This research demonstrates a novel mechanism of ZIKV transmission through multigenome aggregates, providing insight into ZIKV evolution, immunologic evasion, and better future therapeutic design. This study shows that ZIKV plaques result from collections of genomes rather than individual genomes, increasing the potential for interactions between ZIKV genotypes.
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14
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Hill T, Unckless RL. Recurrent evolution of high virulence in isolated populations of a DNA virus. eLife 2020; 9:e58931. [PMID: 33112738 PMCID: PMC7685711 DOI: 10.7554/elife.58931] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Accepted: 10/28/2020] [Indexed: 12/30/2022] Open
Abstract
Hosts and viruses are constantly evolving in response to each other: as a host attempts to suppress a virus, the virus attempts to evade and suppress the host's immune system. Here, we describe the recurrent evolution of a virulent strain of a DNA virus, which infects multiple Drosophila species. Specifically, we identified two distinct viral types that differ 100-fold in viral titer in infected individuals, with similar differences observed in multiple species. Our analysis suggests that one of the viral types recurrently evolved at least four times in the past ~30,000 years, three times in Arizona and once in another geographically distinct species. This recurrent evolution may be facilitated by an effective mutation rate which increases as each prior mutation increases viral titer and effective population size. The higher titer viral type suppresses the host-immune system and an increased virulence compared to the low viral titer type.
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Affiliation(s)
- Tom Hill
- The Department of Molecular Biosciences, University of KansasLawrenceUnited States
| | - Robert L Unckless
- The Department of Molecular Biosciences, University of KansasLawrenceUnited States
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15
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Scroggs SLP, Gass JT, Chinnasamy R, Widen SG, Azar SR, Rossi SL, Arterburn JB, Vasilakis N, Hanley KA. Evolution of resistance to fluoroquinolones by dengue virus serotype 4 provides insight into mechanism of action and consequences for viral fitness. Virology 2020; 552:94-106. [PMID: 33120225 PMCID: PMC7528753 DOI: 10.1016/j.virol.2020.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 08/30/2020] [Accepted: 09/08/2020] [Indexed: 02/07/2023]
Abstract
Drugs against flaviviruses such as dengue (DENV) and Zika (ZIKV) virus are urgently needed. We previously demonstrated that three fluoroquinolones, ciprofloxacin, enoxacin, and difloxacin, suppress replication of six flaviviruses. To investigate the barrier to resistance and mechanism(s) of action of these drugs, DENV-4 was passaged in triplicate in HEK-293 cells in the presence or absence of each drug. Resistance to ciprofloxacin was detected by the seventh passage and to difloxacin by the tenth, whereas resistance to enoxacin did not occur within ten passages. Two putative resistance-conferring mutations were detected in the envelope gene of ciprofloxacin and difloxacin-resistant DENV-4. In the absence of ciprofloxacin, ciprofloxacin-resistant viruses sustained a significantly higher viral titer than control viruses in HEK-293 and HuH-7 cells and resistant viruses were more stable than control viruses at 37 °C. These results suggest that the mechanism of action of ciprofloxacin and difloxacin involves interference with virus binding or entry.
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Affiliation(s)
- Stacey L P Scroggs
- Department of Biology, New Mexico State University, Las Cruces, NM, USA.
| | - Jordan T Gass
- Department of Biology, New Mexico State University, Las Cruces, NM, USA
| | - Ramesh Chinnasamy
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM, USA
| | - Steven G Widen
- Department of Biochemistry & Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA
| | - Sasha R Azar
- Department of Pathology, The University of University of Texas Medical Branch, Galveston, TX, USA
| | - Shannan L Rossi
- Department of Pathology, The University of University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infection and Immunity, The University of University of Texas Medical Branch, Galveston, TX, USA
| | - Jeffrey B Arterburn
- Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, NM, USA
| | - Nikos Vasilakis
- Department of Pathology, The University of University of Texas Medical Branch, Galveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, The University of University of Texas Medical Branch, Galveston, TX, USA; Center for Tropical Diseases, The University of University of Texas Medical Branch, Galveston, TX, USA; Institute for Human Infection and Immunity, The University of University of Texas Medical Branch, Galveston, TX, USA
| | - Kathryn A Hanley
- Department of Biology, New Mexico State University, Las Cruces, NM, USA
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16
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Whitfield ZJ, Prasad AN, Ronk AJ, Kuzmin IV, Ilinykh PA, Andino R, Bukreyev A. Species-Specific Evolution of Ebola Virus during Replication in Human and Bat Cells. Cell Rep 2020; 32:108028. [PMID: 32814037 PMCID: PMC7434439 DOI: 10.1016/j.celrep.2020.108028] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 05/12/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022] Open
Abstract
Ebola virus (EBOV) causes a severe, often fatal disease in humans and nonhuman primates. Within the past decade, EBOV has caused two large and difficult-to-control outbreaks, one of which recently ended in the Democratic Republic of the Congo. Bats are the likely reservoir of EBOV, but little is known of their relationship with the virus. We perform serial passages of EBOV in human and bat cells and use circular sequencing to compare the short-term evolution of the virus. Virus populations passaged in bat cells have sequence markers indicative of host RNA editing enzyme activity, including evidence for ADAR editing of the EBOV glycoprotein. Multiple regions in the EBOV genome appear to have undergone adaptive evolution when passaged in bat and human cells. Individual mutated viruses are rescued and characterized. Our results provide insight into the host species-specific evolution of EBOV and highlight the adaptive flexibility of the virus.
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Affiliation(s)
- Zachary J Whitfield
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Abhishek N Prasad
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Adam J Ronk
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Ivan V Kuzmin
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Philipp A Ilinykh
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, USA
| | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA.
| | - Alexander Bukreyev
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, USA; Department Microbiology & Immunology, University of Texas Medical Branch, Galveston, TX, USA; Galveston National Laboratory, University of Texas Medical Branch, Galveston, TX, USA.
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17
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Caldwell HS, Ngo K, Pata JD, Kramer LD, Ciota AT. West Nile Virus fidelity modulates the capacity for host cycling and adaptation. J Gen Virol 2020; 101:410-419. [PMID: 32068528 DOI: 10.1099/jgv.0.001393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The fidelity of flaviviruses is thought to be tightly regulated for optimal fitness within and between hosts. West Nile virus (WNV) high-fidelity (HiFi) mutations V793I and G806R within the RNA-dependent RNA polymerase, and low-fidelity (LoFi) mutation T248I within the methyltransferase, were previously shown to attenuate infectivity and replicative fitness in Culex mosquitoes and Culex tarsalis (CXT) cells but not in mammalian cells. We hypothesized that fidelity alterations would modify adaptation and maintenance in a host-specific manner. To test this hypothesis, wild-type (WT), HiFi (V793I/G806R) and LoFi (T248I) variants were sequentially passaged eight times in avian (PDE) or mosquito cells, or alternately between the two. Initial characterization confirmed that fidelity mutants are attenuated in mosquito, but not avian, cells. Deep sequencing revealed mutations unique to both cell lines and fidelity mutants, including ENV G1378A, a mutation associated with avian cell adaptation. To characterize maintenance and adaptation, viral outputs were monitored throughout passaging and viral fitness was assessed. The results indicate that fidelity mutants can at times recover fitness during mosquito cell passage, but remain attenuated relative to WT. Despite similar initial fitness, LoFi mutants were impaired during sequential passage in avian cells. Conversely, HiFi mutants passaged in avian cells showed increased adaptation, suggesting that increased fidelity may be advantageous in avian hosts. Although some adaptation occurred with individual mutants, the output titres of fidelity mutants were on average lower and were often lost during host switching. These data confirm that arbovirus fidelity is likely fine-tuned to maximize survival in disparate hosts.
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Affiliation(s)
- Haley S Caldwell
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY, USA.,Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, NY, USA
| | - Kiet Ngo
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY, USA
| | - Janice D Pata
- Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, NY, USA
| | - Laura D Kramer
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY, USA.,Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, NY, USA
| | - Alexander T Ciota
- The Arbovirus Laboratory, Wadsworth Center, New York State Department of Health, Slingerlands, NY, USA.,Department of Biomedical Sciences, State University of New York at Albany School of Public Health, Albany, NY, USA
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An RNA Thermometer Activity of the West Nile Virus Genomic 3'-Terminal Stem-Loop Element Modulates Viral Replication Efficiency during Host Switching. Viruses 2020; 12:v12010104. [PMID: 31952291 PMCID: PMC7019923 DOI: 10.3390/v12010104] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/20/2019] [Accepted: 01/12/2020] [Indexed: 02/07/2023] Open
Abstract
The 3′-terminal stem-loop (3′SL) of the RNA genome of the flavivirus West Nile (WNV) harbors, in its stem, one of the sequence elements that are required for genome cyclization. As cyclization is a prerequisite for the initiation of viral replication, the 3′SL was proposed to act as a replication silencer. The lower part of the 3′SL is metastable and confers a structural flexibility that may regulate the switch from the linear to the circular conformation of the viral RNA. In the human system, we previously demonstrated that a cellular RNA-binding protein, AUF1 p45, destabilizes the 3′SL, exposes the cyclization sequence, and thus promotes flaviviral genome cyclization and RNA replication. By investigating mutant RNAs with increased 3′SL stabilities, we showed the specific conformation of the metastable element to be a critical determinant of the helix-destabilizing RNA chaperone activity of AUF1 p45 and of the precision and efficiency of the AUF1 p45-supported initiation of RNA replication. Studies of stability-increasing mutant WNV replicons in human and mosquito cells revealed that the cultivation temperature considerably affected the replication efficiencies of the viral RNA variants and demonstrated the silencing effect of the 3′SL to be temperature dependent. Furthermore, we identified and characterized mosquito proteins displaying similar activities as AUF1 p45. However, as the RNA remodeling activities of the mosquito proteins were found to be considerably lower than those of the human protein, a potential cell protein-mediated destabilization of the 3′SL was suggested to be less efficient in mosquito cells. In summary, our data support a model in which the 3′SL acts as an RNA thermometer that modulates flavivirus replication during host switching.
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Comparative Pathology of West Nile Virus in Humans and Non-Human Animals. Pathogens 2020; 9:pathogens9010048. [PMID: 31935992 PMCID: PMC7168622 DOI: 10.3390/pathogens9010048] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/03/2020] [Accepted: 01/03/2020] [Indexed: 12/11/2022] Open
Abstract
West Nile virus (WNV) continues to be a major cause of human arboviral neuroinvasive disease. Susceptible non-human vertebrates are particularly diverse, ranging from commonly affected birds and horses to less commonly affected species such as alligators. This review summarizes the pathology caused by West Nile virus during natural infections of humans and non-human animals. While the most well-known findings in human infection involve the central nervous system, WNV can also cause significant lesions in the heart, kidneys and eyes. Time has also revealed chronic neurologic sequelae related to prior human WNV infection. Similarly, neurologic disease is a prominent manifestation of WNV infection in most non-human non-host animals. However, in some avian species, which serve as the vertebrate host for WNV maintenance in nature, severe systemic disease can occur, with neurologic, cardiac, intestinal and renal injury leading to death. The pathology seen in experimental animal models of West Nile virus infection and knowledge gains on viral pathogenesis derived from these animal models are also briefly discussed. A gap in the current literature exists regarding the relationship between the neurotropic nature of WNV in vertebrates, virus propagation and transmission in nature. This and other knowledge gaps, and future directions for research into WNV pathology, are addressed.
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20
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Kuny CV, Bowen CD, Renner DW, Johnston CM, Szpara ML. In vitro evolution of herpes simplex virus 1 (HSV-1) reveals selection for syncytia and other minor variants in cell culture. Virus Evol 2020; 6:veaa013. [PMID: 32296542 PMCID: PMC7151645 DOI: 10.1093/ve/veaa013] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The large dsDNA virus herpes simplex virus 1 (HSV-1) is considered to be genetically stable, yet it can rapidly evolve in response to strong selective pressures such as antiviral treatment. Deep sequencing has revealed that clinical and laboratory isolates of this virus exist as populations that contain a mixture of minor alleles or variants, similar to many RNA viruses. The classic virology approach of plaque purifying virus creates a genetically homogenous population, but it is not clear how closely this represents the mixed virus populations found in nature. We sought to study the evolution of mixed versus highly purified HSV-1 populations in controlled cell culture conditions, to examine the impact of this genetic diversity on evolution. We found that a mixed population of HSV-1 acquired more genetic diversity and underwent a more dramatic phenotypic shift than a plaque-purified population, producing a viral population that was almost entirely syncytial after just ten passages. At the genomic level, adaptation and genetic diversification occurred at the level of minor alleles or variants in the viral population. Certain genetic variants in the mixed viral population appeared to be positively selected in cell culture, and this shift was also observed in clinical samples during their first passages in vitro. In contrast, the plaque-purified viral population did not appear to change substantially in phenotype or overall quantity of minor allele diversity. These data indicate that HSV-1 is capable of evolving rapidly in a given environment, and that this evolution is facilitated by diversity in the viral population.
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Affiliation(s)
- Chad V Kuny
- Departments of Biology, and Biochemistry and Molecular Biology, The Huck Institutes of the Life Sciences, and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Christopher D Bowen
- Departments of Biology, and Biochemistry and Molecular Biology, The Huck Institutes of the Life Sciences, and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Daniel W Renner
- Departments of Biology, and Biochemistry and Molecular Biology, The Huck Institutes of the Life Sciences, and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
| | - Christine M Johnston
- Department of Medicine, University of Washington, Seattle, WA, USA
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Moriah L Szpara
- Departments of Biology, and Biochemistry and Molecular Biology, The Huck Institutes of the Life Sciences, and Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA
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21
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Duggal NK, Langwig KE, Ebel GD, Brault AC. On the Fly: Interactions Between Birds, Mosquitoes, and Environment That Have Molded West Nile Virus Genomic Structure Over Two Decades. JOURNAL OF MEDICAL ENTOMOLOGY 2019; 56:1467-1474. [PMID: 31549720 PMCID: PMC7182917 DOI: 10.1093/jme/tjz112] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Indexed: 05/15/2023]
Abstract
West Nile virus (WNV) was first identified in North America almost 20 yr ago. In that time, WNV has crossed the continent and established enzootic transmission cycles, resulting in intermittent outbreaks of human disease that have largely been linked with climatic variables and waning avian seroprevalence. During the transcontinental dissemination of WNV, the original genotype has been displaced by two principal extant genotypes which contain an envelope mutation that has been associated with enhanced vector competence by Culex pipiens L. (Diptera: Culicidae) and Culex tarsalis Coquillett vectors. Analyses of retrospective avian host competence data generated using the founding NY99 genotype strain have demonstrated a steady reduction in viremias of house sparrows over time. Reciprocally, the current genotype strains WN02 and SW03 have demonstrated an inverse correlation between house sparrow viremia magnitude and the time since isolation. These data collectively indicate that WNV has evolved for increased avian viremia while house sparrows have evolved resistance to the virus such that the relative host competence has remained constant. Intrahost analyses of WNV evolution demonstrate that selection pressures are avian species-specific and purifying selection is greater in individual birds compared with individual mosquitoes, suggesting that the avian adaptive and/or innate immune response may impose a selection pressure on WNV. Phylogenomic, experimental evolutionary systems, and models that link viral evolution with climate, host, and vector competence studies will be needed to identify the relative effect of different selective and stochastic mechanisms on viral phenotypes and the capacity of newly evolved WNV genotypes for transmission in continuously changing landscapes.
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Affiliation(s)
- Nisha K Duggal
- Department of Biomedical Sciences and Pathobiology, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Kate E Langwig
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA
| | - Gregory D Ebel
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO
| | - Aaron C Brault
- Division of Vector-borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO
- Corresponding author, e-mail:
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22
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Hadfield J, Brito AF, Swetnam DM, Vogels CBF, Tokarz RE, Andersen KG, Smith RC, Bedford T, Grubaugh ND. Twenty years of West Nile virus spread and evolution in the Americas visualized by Nextstrain. PLoS Pathog 2019; 15:e1008042. [PMID: 31671157 PMCID: PMC6822705 DOI: 10.1371/journal.ppat.1008042] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
It has been 20 years since West Nile virus first emerged in the Americas, and since then, little progress has been made to control outbreaks caused by this virus. After its first detection in New York in 1999, West Nile virus quickly spread across the continent, causing an epidemic of human disease and massive bird die-offs. Now the virus has become endemic to the United States, where an estimated 7 million human infections have occurred, making it the leading mosquito-borne virus infection and the most common cause of viral encephalitis in the country. To bring new attention to one of the most important mosquito-borne viruses in the Americas, we provide an interactive review using Nextstrain: a visualization tool for real-time tracking of pathogen evolution (nextstrain.org/WNV/NA). Nextstrain utilizes a growing database of more than 2,000 West Nile virus genomes and harnesses the power of phylogenetics for students, educators, public health workers, and researchers to visualize key aspects of virus spread and evolution. Using Nextstrain, we use virus genomics to investigate the emergence of West Nile virus in the U S, followed by its rapid spread, evolution in a new environment, establishment of endemic transmission, and subsequent international spread. For each figure, we include a link to Nextstrain to allow the readers to directly interact with and explore the underlying data in new ways. We also provide a brief online narrative that parallels this review to further explain the data and highlight key epidemiological and evolutionary features (nextstrain.org/narratives/twenty-years-of-WNV). Mirroring the dynamic nature of outbreaks, the Nextstrain links provided within this paper are constantly updated as new West Nile virus genomes are shared publicly, helping to stay current with the research. Overall, our review showcases how genomics can track West Nile virus spread and evolution, as well as potentially uncover novel targeted control measures to help alleviate its public health burden.
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Affiliation(s)
- James Hadfield
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Anderson F. Brito
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Daniele M. Swetnam
- Department of Pathology, Microbiology and Immunology, University of California, Davis, Davis, California, United States of America
| | - Chantal B. F. Vogels
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
| | - Ryan E. Tokarz
- Department of Entomology, Iowa State University, Ames, Iowa, United States of America
| | - Kristian G. Andersen
- Department of Immunology and Microbiology, Scripps Research, La Jolla, California, United States of America
- Scripps Research Translational Institute, La Jolla, California, United States of America
| | - Ryan C. Smith
- Department of Entomology, Iowa State University, Ames, Iowa, United States of America
| | - Trevor Bedford
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Nathan D. Grubaugh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, Connecticut, United States of America
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23
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Sexton NR, Ebel GD. Effects of Arbovirus Multi-Host Life Cycles on Dinucleotide and Codon Usage Patterns. Viruses 2019; 11:v11070643. [PMID: 31336898 PMCID: PMC6669465 DOI: 10.3390/v11070643] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/09/2019] [Accepted: 07/11/2019] [Indexed: 12/12/2022] Open
Abstract
Arthropod-borne viruses (arboviruses) of vertebrates including dengue, zika, chikungunya, Rift Valley fever, and blue tongue viruses cause extensive morbidity and mortality in humans, agricultural animals, and wildlife across the globe. As obligate intercellular pathogens, arboviruses must be well adapted to the cellular and molecular environment of both their arthropod (invertebrate) and vertebrate hosts, which are vastly different due to hundreds of millions of years of separate evolution. Here we discuss the comparative pressures on arbovirus RNA genomes as a result of a dual host life cycle, focusing on pressures that do not alter amino acids. We summarize what is currently known about arboviral genetic composition, such as dinucleotide and codon usage, and how cyclical infection of vertebrate and invertebrate hosts results in different genetic profiles compared with single-host viruses. To serve as a comparison, we compile what is known about arthropod tRNA, dinucleotide, and codon usages and compare this with vertebrates. Additionally, we discuss the potential roles of genetic robustness in arboviral evolution and how it may vary from other viruses. Overall, both arthropod and vertebrate hosts influence the resulting genetic composition of arboviruses, but a great deal remains to be investigated.
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Affiliation(s)
- Nicole R Sexton
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Gregory D Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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24
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Endless Forms: Within-Host Variation in the Structure of the West Nile Virus RNA Genome during Serial Passage in Bird Hosts. mSphere 2019; 4:4/3/e00291-19. [PMID: 31243074 PMCID: PMC6595145 DOI: 10.1128/msphere.00291-19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The enzymes that copy RNA genomes lack proofreading, and viruses that possess RNA genomes, such as West Nile virus, rapidly diversify into swarms of mutant lineages within a host. Intrahost variation of the primary genomic sequence of RNA viruses has been studied extensively because the extent of this variation shapes key virus phenotypes. However, RNA genomes also form complex secondary structures based on within-genome nucleotide complementarity, which are critical regulators of the cyclization of the virus genome that is necessary for efficient replication and translation. We sought to characterize variation in these secondary structures within populations of West Nile virus during serial passage in three bird species. Our study indicates that the intrahost population of West Nile virus is a diverse assortment of RNA secondary structures that should be considered in future analyses of intrahost viral diversity, but some regions that are critical for genome cyclization are conserved within hosts. Besides potential impacts on viral replication, structural diversity can influence the efficacy of small RNA antiviral therapies. RNA viruses are infamous for their high rates of mutation, which produce swarms of genetic variants within individual hosts. To date, analyses of intrahost genetic diversity have focused on the primary genome sequence. However, virus phenotypes are shaped not only by primary sequence but also by the secondary structures into which this sequence folds. Such structures enable viral replication, translation, and binding of small RNAs, yet within-host variation at the structural level has not been adequately explored. We characterized the structural diversity of the 5′ untranslated region (UTR) of populations of West Nile virus (WNV) that had been subject to five serial passages in triplicate in each of three bird species. Viral genomes were sampled from host serum samples at each passage (n = 45 populations) and subjected to next-generation sequencing. For populations derived from passages 1, 3, and 5 (n = 9 populations), we predicted the impact of each mutation occurring at a frequency of ≥1% on the secondary structure of the 5′ UTR. As expected, mutations in double-stranded (DS) regions of the 5′ UTR stem structures caused structural changes of significantly greater magnitude than did mutations in single-stranded (SS) regions. Despite the greater impact of mutations in DS regions, mutations in DS and SS regions occurred at similar frequencies, with no evidence of enhanced selection against mutation in DS regions. In contrast, mutations in two regions that mediate genome cyclization and thereby regulate replication and translation, the 5′ cyclization sequence and the UAR flanking stem (UFS), were suppressed in all three hosts. IMPORTANCE The enzymes that copy RNA genomes lack proofreading, and viruses that possess RNA genomes, such as West Nile virus, rapidly diversify into swarms of mutant lineages within a host. Intrahost variation of the primary genomic sequence of RNA viruses has been studied extensively because the extent of this variation shapes key virus phenotypes. However, RNA genomes also form complex secondary structures based on within-genome nucleotide complementarity, which are critical regulators of the cyclization of the virus genome that is necessary for efficient replication and translation. We sought to characterize variation in these secondary structures within populations of West Nile virus during serial passage in three bird species. Our study indicates that the intrahost population of West Nile virus is a diverse assortment of RNA secondary structures that should be considered in future analyses of intrahost viral diversity, but some regions that are critical for genome cyclization are conserved within hosts. Besides potential impacts on viral replication, structural diversity can influence the efficacy of small RNA antiviral therapies.
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25
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Koh C, Audsley MD, Di Giallonardo F, Kerton EJ, Young PR, Holmes EC, McGraw EA. Sustained Wolbachia-mediated blocking of dengue virus isolates following serial passage in Aedes aegypti cell culture. Virus Evol 2019; 5:vez012. [PMID: 31191980 PMCID: PMC6555872 DOI: 10.1093/ve/vez012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Wolbachia is an intracellular endosymbiont of insects that inhibits the replication of a range of pathogens in its arthropod hosts. The release of Wolbachia into wild populations of mosquitoes is an innovative biocontrol effort to suppress the transmission of arthropod-borne viruses (arboviruses) to humans, most notably dengue virus. The success of the Wolbachia-based approach hinges upon the stable persistence of the ‘pathogen blocking’ effect, whose mechanistic basis is poorly understood. Evidence suggests that Wolbachia may affect viral replication via a combination of competition for host resources and activation of host immunity. The evolution of resistance against Wolbachia and pathogen blocking in the mosquito or the virus could reduce the public health impact of the symbiont releases. Here, we investigate if dengue 3 virus (DENV-3) is capable of accumulating adaptive mutations that improve its replicative capacity during serial passage in Wolbachia wMel-infected cells. During the passaging regime, viral isolates in Wolbachia-infected cells exhibited greater variation in viral loads compared to controls. The viral loads of these isolates declined rapidly during passaging due to the blocking effects of Wolbachia carriage, with several being lost all together and the remainder recovering to low but stable levels. We attempted to sequence the genomes of the surviving passaged isolates but, given their low abundance, were unable to obtain sufficient depth of coverage for evolutionary analysis. In contrast, viral loads in Wolbachia-free control cells were consistently high during passaging. The surviving isolates passaged in the presence of Wolbachia exhibited a reduced ability to replicate even in Wolbachia-free cells. These experiments demonstrate the challenge for dengue in evolving resistance to Wolbachia-mediated blocking.
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Affiliation(s)
- Cassandra Koh
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Michelle D Audsley
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Francesca Di Giallonardo
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW, Australia.,Sydney Medical School, The University of Sydney, Camperdown, NSW, Australia.,The Kirby Institute, School of Medical Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Emily J Kerton
- School of Biological Sciences, Monash University, Clayton, VIC, Australia
| | - Paul R Young
- Australian Infectious Diseases Research Centre, School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, QLD, Australia
| | - Edward C Holmes
- Marie Bashir Institute for Infectious Diseases and Biosecurity, Charles Perkins Centre, School of Life and Environmental Sciences, The University of Sydney, Camperdown, NSW, Australia
| | - Elizabeth A McGraw
- School of Biological Sciences, Monash University, Clayton, VIC, Australia.,Department of Entomology, Center for Infectious Disease Dynamics, Huck Institutes of the Life Sciences, Pennsylvania State University, State College, PA, USA
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26
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Swamy KBS, Zhou N. Experimental evolution: its principles and applications in developing stress-tolerant yeasts. Appl Microbiol Biotechnol 2019; 103:2067-2077. [PMID: 30659332 DOI: 10.1007/s00253-019-09616-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 01/03/2019] [Accepted: 01/03/2019] [Indexed: 10/27/2022]
Abstract
Stress tolerance and resistance in industrial yeast strains are important attributes for cost-effective bioprocessing. The source of stress-tolerant yeasts ranges from extremophilic environments to laboratory engineered strains. However, industrial stress-tolerant yeasts are very rare in nature as the natural environment forces them to evolve traits that optimize survival and reproduction and not the ability to withstand harsh habitat-irrelevant industrial conditions. Experimental evolution is a frequent method used to uncover the mechanisms of evolution and microbial adaption towards environmental stresses. It optimizes biological systems by means of adaptation to environmental stresses and thus has immense power of development of robust stress-tolerant yeasts. This mini-review briefly outlines the basics and implications of evolution experiments and their applications to industrial biotechnology. This work is meant to serve as an introduction to those new to the field of experimental evolution, and as a guide to biologists working in the field of yeast stress response. Future perspectives of experimental evolution for potential biotechnological applications have also been elucidated.
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Affiliation(s)
| | - Nerve Zhou
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P Bag 16, Palapye, Botswana
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27
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Grubaugh ND, Gangavarapu K, Quick J, Matteson NL, De Jesus JG, Main BJ, Tan AL, Paul LM, Brackney DE, Grewal S, Gurfield N, Van Rompay KKA, Isern S, Michael SF, Coffey LL, Loman NJ, Andersen KG. An amplicon-based sequencing framework for accurately measuring intrahost virus diversity using PrimalSeq and iVar. Genome Biol 2019; 20:8. [PMID: 30621750 PMCID: PMC6325816 DOI: 10.1186/s13059-018-1618-7] [Citation(s) in RCA: 542] [Impact Index Per Article: 108.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 12/26/2018] [Indexed: 01/17/2023] Open
Abstract
How viruses evolve within hosts can dictate infection outcomes; however, reconstructing this process is challenging. We evaluate our multiplexed amplicon approach, PrimalSeq, to demonstrate how virus concentration, sequencing coverage, primer mismatches, and replicates influence the accuracy of measuring intrahost virus diversity. We develop an experimental protocol and computational tool, iVar, for using PrimalSeq to measure virus diversity using Illumina and compare the results to Oxford Nanopore sequencing. We demonstrate the utility of PrimalSeq by measuring Zika and West Nile virus diversity from varied sample types and show that the accumulation of genetic diversity is influenced by experimental and biological systems.
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Affiliation(s)
- Nathan D Grubaugh
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA.
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, 06510, USA.
| | - Karthik Gangavarapu
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA.
| | - Joshua Quick
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Nathaniel L Matteson
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Jaqueline Goes De Jesus
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
- Laboratory of Experimental Pathology, Gonçalo Moniz Institute, Oswaldo Cruz Foundation, Salvador, Bahia, Brazil
| | - Bradley J Main
- Department of Pathology, Microbiology and Immunology, University of California, Davis, CA, 95616, USA
| | - Amanda L Tan
- Department of Biological Sciences, College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, FL, 33965, USA
| | - Lauren M Paul
- Department of Biological Sciences, College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, FL, 33965, USA
| | - Doug E Brackney
- Department of Environmental Sciences, The Connecticut Agricultural Experiment Station, New Haven, CT, 06504, USA
| | - Saran Grewal
- Department of Environmental Health, San Diego County Vector Control Program, San Diego, CA, 92123, USA
| | - Nikos Gurfield
- Department of Environmental Health, San Diego County Vector Control Program, San Diego, CA, 92123, USA
| | - Koen K A Van Rompay
- California National Primate Research Center and Department of Pathology, Microbiology and Immunology, University of California, Davis, CA, 95616, USA
| | - Sharon Isern
- Department of Biological Sciences, College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, FL, 33965, USA
| | - Scott F Michael
- Department of Biological Sciences, College of Arts and Sciences, Florida Gulf Coast University, Fort Myers, FL, 33965, USA
| | - Lark L Coffey
- Department of Pathology, Microbiology and Immunology, University of California, Davis, CA, 95616, USA
| | - Nicholas J Loman
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, B15 2TT, UK
| | - Kristian G Andersen
- Department of Immunology and Microbiology, The Scripps Research Institute, La Jolla, CA, 92037, USA
- Scripps Research Translational Institute, La Jolla, CA, 92037, USA
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28
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Dolan PT, Whitfield ZJ, Andino R. Mechanisms and Concepts in RNA Virus Population Dynamics and Evolution. Annu Rev Virol 2018; 5:69-92. [PMID: 30048219 DOI: 10.1146/annurev-virology-101416-041718] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
RNA viruses are unique in their evolutionary capacity, exhibiting high mutation rates and frequent recombination. They rapidly adapt to environmental changes, such as shifts in immune pressure or pharmacological challenge. The evolution of RNA viruses has been brought into new focus with the recent developments of genetic and experimental tools to explore and manipulate the evolutionary dynamics of viral populations. These studies have uncovered new mechanisms that enable viruses to overcome evolutionary challenges in the environment and have emphasized the intimate relationship of viral populations with evolution. Here, we review some of the emerging viral and host mechanisms that underlie the evolution of RNA viruses. We also discuss new studies that demonstrate that the relationship between evolutionary dynamics and virus biology spans many spatial and temporal scales, affecting transmission dynamics within and between hosts as well as pathogenesis.
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Affiliation(s)
- Patrick T Dolan
- Department of Biology, Stanford University, Stanford, California 94305, USA.,Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA;
| | - Zachary J Whitfield
- Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA;
| | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, California 94143, USA;
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29
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Abstract
The deterministic force of natural selection and stochastic influence of drift shape RNA virus evolution. New deep-sequencing and microfluidics technologies allow us to quantify the effect of mutations and trace the evolution of viral populations with single-genome and single-nucleotide resolution. Such experiments can reveal the topography of the genotype-fitness landscapes that shape the path of viral evolution. By combining historical analyses, like phylogenetic approaches, with high-throughput and high-resolution evolutionary experiments, we can observe parallel patterns of evolution that drive important phenotypic transitions. These developments provide a framework for quantifying and anticipating potential evolutionary events. Here, we examine emerging technologies that can map the selective landscapes of viruses, focusing on their application to pathogenic viruses. We identify areas where these technologies can bolster our ability to study the evolution of viruses and to anticipate and possibly intervene in evolutionary events and prevent viral disease.
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Affiliation(s)
- Patrick T Dolan
- Department of Biology, Stanford University, E200 Clark Center, 318 Campus Drive, Stanford, CA 94305, USA; Department of Microbiology and Immunology, University of California, San Francisco, 600 16th Street, GH-S572, UCSF Box 2280, San Francisco, CA 94143-2280, USA
| | - Zachary J Whitfield
- Department of Microbiology and Immunology, University of California, San Francisco, 600 16th Street, GH-S572, UCSF Box 2280, San Francisco, CA 94143-2280, USA
| | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, 600 16th Street, GH-S572, UCSF Box 2280, San Francisco, CA 94143-2280, USA.
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30
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Kautz TF, Guerbois M, Khanipov K, Patterson EI, Langsjoen RM, Yun R, Warmbrod KL, Fofanov Y, Weaver SC, Forrester NL. Low-fidelity Venezuelan equine encephalitis virus polymerase mutants to improve live-attenuated vaccine safety and efficacy. Virus Evol 2018; 4:vey004. [PMID: 29593882 PMCID: PMC5841381 DOI: 10.1093/ve/vey004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
During RNA virus replication, there is the potential to incorporate mutations that affect virulence or pathogenesis. For live-attenuated vaccines, this has implications for stability, as replication may result in mutations that either restore the wild-type phenotype via reversion or compensate for the attenuating mutations by increasing virulence (pseudoreversion). Recent studies have demonstrated that altering the mutation rate of an RNA virus is an effective attenuation tool. To validate the safety of low-fidelity mutations to increase vaccine attenuation, several mutations in the RNA-dependent RNA-polymerase (RdRp) were tested in the live-attenuated Venezuelan equine encephalitis virus vaccine strain, TC-83. Next generation sequencing after passage in the presence of mutagens revealed a mutant containing three mutations in the RdRp, TC-83 3x, to have decreased replication fidelity, while a second mutant, TC-83 4x displayed no change in fidelity, but shared many phenotypic characteristics with TC-83 3x. Both mutants exhibited increased, albeit inconsistent attenuation in an infant mouse model, as well as increased immunogenicity and complete protection against lethal challenge of an adult murine model compared with the parent TC-83. During serial passaging in a highly permissive model, the mutants increased in virulence but remained less virulent than the parent TC-83. These results suggest that the incorporation of low-fidelity mutations into the RdRp of live-attenuated vaccines for RNA viruses can confer increased immunogenicity whilst showing some evidence of increased attenuation. However, while in theory such constructs may result in more effective vaccines, the instability of the vaccine phenotype decreases the likelihood of this being an effective vaccine strategy.
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Affiliation(s)
- Tiffany F Kautz
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA
| | - Mathilde Guerbois
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Kamil Khanipov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Edward I Patterson
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Rose M Langsjoen
- Institute for Translational Sciences, University of Texas Medical Branch, Galveston, TX, USA
| | - Ruimei Yun
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Kelsey L Warmbrod
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Yuriy Fofanov
- Department of Pharmacology and Toxicology, Sealy Center for Structural Biology and Molecular Biophysics, University of Texas Medical Branch, Galveston, TX, USA
| | - Scott C Weaver
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, USA.,Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - Naomi L Forrester
- Department of Pathology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
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31
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Mosquitoes Transmit Unique West Nile Virus Populations during Each Feeding Episode. Cell Rep 2018; 19:709-718. [PMID: 28445723 DOI: 10.1016/j.celrep.2017.03.076] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 01/26/2017] [Accepted: 03/28/2017] [Indexed: 11/23/2022] Open
Abstract
Arthropod-borne viruses (arboviruses), such as Zika virus, chikungunya virus, and West Nile virus (WNV), pose continuous threats to emerge and cause large epidemics. Often, these events are associated with novel virus variants optimized for local transmission that first arise as minorities within a host. Thus, the conditions that regulate the frequency of intrahost variants are important determinants of emergence. Here, we describe the dynamics of WNV genetic diversity during its transmission cycle. By temporally sampling saliva from individual mosquitoes, we demonstrate that virus populations expectorated by mosquitoes are highly diverse and unique to each feeding episode. After transmission to birds, however, most genetic diversity is removed by strong purifying selection. Further, transmission of potentially mosquito-adaptive WNV variants is strongly influenced by genetic drift in mosquitoes. These results highlight the complex evolutionary forces a novel virus variant must overcome to alter infection phenotypes at the population level.
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32
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Nelson CW, Sibley SD, Kolokotronis SO, Hamer GL, Newman CM, Anderson TK, Walker ED, Kitron UD, Brawn JD, Ruiz MO, Goldberg TL. Selective constraint and adaptive potential of West Nile virus within and among naturally infected avian hosts and mosquito vectors. Virus Evol 2018; 4:vey013. [PMID: 29942654 PMCID: PMC6007309 DOI: 10.1093/ve/vey013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Arthropod-borne viruses are among the most genetically constrained RNA viruses, yet they have a remarkable propensity to adapt and emerge. We studied wild birds and mosquitoes naturally infected with West Nile virus (WNV) in a 'hot spot' of virus transmission in Chicago, IL, USA. We generated full coding WNV genome sequences from spatiotemporally matched bird and mosquito samples using high-throughput sequencing, allowing a molecular evolutionary assessment with deep coverage. Mean FST among samples was 0.66 (±0.02 SE) and was bimodal, with mean nucleotide diversity being higher between samples (interhost πN = 0.001; πS = 0.024) than within them (intrahost πN < 0.0001; πS < 0.001). Eight genomic sites with FST > 1.01 (in the PrM, NS2a, NS3, NS4b, and 5'-noncoding genomic regions) showed bird versus mosquito variant frequency differences of >30 per cent and/or polymorphisms fixed in ≥5 host or vector individuals, suggesting host tropism for these variants. However, phylogenetic analyses demonstrated a lack of grouping by bird or mosquito, most inter-sample differences were synonymous (mean interhost πN/πS = 0.04), and there was no significant difference between hosts and vectors in either their nucleotide diversities or levels of purifying selection (mean intrahost πN/πS = 0.28 in birds and πN/πS = 0.21 in mosquitoes). This finding contrasts with the 'trade-off' and 'selective sieve' hypotheses that have been proposed and tested in the laboratory, which predict strong host versus vector effects on WNV genetic variation, with heightened selective constraint in birds alternating with heightened viral diversity in mosquitoes. Overall, our data show WNV to be highly selectively constrained within and between both hosts and vectors but still able to vary at a limited number of sites across the genome. Such site-specific plasticity in the face of overall selective constraint may offer a mechanism whereby highly constrained viruses such as WNV and its relatives can still adapt and emerge.
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Affiliation(s)
- Chase W Nelson
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY 10024, USA
| | - Samuel D Sibley
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Sergios-Orestis Kolokotronis
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, NY 10024, USA
- Department of Epidemiology and Biostatistics, School of Public Health, SUNY Downstate Medical Center, Brooklyn, NY 11203-2098, USA
| | - Gabriel L Hamer
- Department of Entomology, Texas A&M University, College Station, TX 77843-2475, USA
| | - Christina M Newman
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Tavis K Anderson
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Edward D Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, Lansing, MI 48824-4320, USA
| | - Uriel D Kitron
- Department of Environmental Studies, Emory University, Atlanta, GA 30322, USA
| | - Jeffrey D Brawn
- Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, IL 61801, USA
| | - Marilyn O Ruiz
- Department of Pathobiology, University of Illinois, Urbana, IL 61802, USA
| | - Tony L Goldberg
- Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI 53706, USA
- Global Health Institute, University of Wisconsin-Madison, Madison, WI 53706, USA
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33
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Smith DR, Sprague TR, Hollidge BS, Valdez SM, Padilla SL, Bellanca SA, Golden JW, Coyne SR, Kulesh DA, Miller LJ, Haddow AD, Koehler JW, Gromowski GD, Jarman RG, Alera MTP, Yoon IK, Buathong R, Lowen RG, Kane CD, Minogue TD, Bavari S, Tesh RB, Weaver SC, Linthicum KJ, Pitt ML, Nasar F. African and Asian Zika Virus Isolates Display Phenotypic Differences Both In Vitro and In Vivo. Am J Trop Med Hyg 2017; 98:432-444. [PMID: 29280428 DOI: 10.4269/ajtmh.17-0685] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Zika virus (ZIKV) is a mosquito-borne member of the genus Flavivirus that has emerged since 2007 to cause outbreaks in Africa, Asia, Oceania, and most recently, in the Americas. Here, we used an isolate history as well as genetic and phylogenetic analyses to characterize three low-passage isolates representing African (ArD 41525) and Asian (CPC-0740, SV0127-14) lineages to investigate the potential phenotypic differences in vitro and in vivo. The African isolate displayed a large plaque phenotype (∼3-4 mm) on Vero and HEK-293 cells, whereas the Asian isolates either exhibited a small plaque phenotype (∼1-2 mm) or did not produce any plaques. In multistep replication kinetics in nine different vertebrate and insect cell lines, the African isolate consistently displayed faster replication kinetics and yielded ∼10- to 10,000-fold higher peak virus titers (infectious or RNA copies) compared with the Asian isolates. Oral exposure of Aedes aegypti mosquitoes with the African isolate yielded higher infection and dissemination rates compared with the Asian isolates. Infection of Ifnar1-/- mice with the African isolate produced a uniformly fatal disease, whereas infection with the Asian isolates produced either a delay in time-to-death or a significantly lower mortality rate. Last, the African isolate was > 10,000-fold more virulent than the Asian isolates in an interferon type I antibody blockade mouse model. These data demonstrate substantial phenotypic differences between low-passage African and Asian isolates both in vitro and in vivo and warrant further investigation. They also highlight the need for basic characterization of ZIKV isolates, as the utilization of the uncharacterized isolates could have consequences for animal model and therapeutic/vaccine development.
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Affiliation(s)
- Darci R Smith
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Thomas R Sprague
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Bradley S Hollidge
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Stephanie M Valdez
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Susana L Padilla
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Stephanie A Bellanca
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Joseph W Golden
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Susan R Coyne
- Diagnostics Systems Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - David A Kulesh
- Diagnostics Systems Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Lynn Jean Miller
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Andrew D Haddow
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Jeff W Koehler
- Diagnostics Systems Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | | | | | - Maria Theresa P Alera
- Department of Virology, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | - In-Kyu Yoon
- International Vaccine Institute, Seoul, Republic of Korea
| | - Rome Buathong
- Department of Disease Control, Bureau of Epidemiology, Ministry of Public Health, Nonthaburi, Thailand
| | - Robert G Lowen
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Christopher D Kane
- Molecular and Translational Sciences Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Timothy D Minogue
- Diagnostics Systems Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Sina Bavari
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Robert B Tesh
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas.,Department of Pathology, University of Texas Medical Branch, Galveston, Texas.,Institute for Human Infections and Immunity, Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas
| | - Scott C Weaver
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas.,Department of Pathology, University of Texas Medical Branch, Galveston, Texas.,Institute for Human Infections and Immunity, Center for Tropical Diseases, University of Texas Medical Branch, Galveston, Texas
| | - Kenneth J Linthicum
- Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, Florida
| | - Margaret L Pitt
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland
| | - Farooq Nasar
- Virology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, Maryland.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas
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34
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Hoon-Hanks LL, McGrath S, Tyler KL, Owen C, Stenglein MD. Metagenomic Investigation of Idiopathic Meningoencephalomyelitis in Dogs. J Vet Intern Med 2017; 32:324-330. [PMID: 29197179 PMCID: PMC5787199 DOI: 10.1111/jvim.14877] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 08/11/2017] [Accepted: 10/17/2017] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Meningoencephalomyelitis of unknown origin (MUO) is a common and life-threatening neuroinflammatory disease in dogs. Features of the disease are suggestive of an underlying immune-mediated process, but the association of this disease with a pathogen is still unknown. HYPOTHESIS/OBJECTIVES To search for candidate etiologic agent associated with cases if MUO using next generation metagenomic sequencing. ANIMALS Twenty-two dogs diagnosed with either MUO (11/22; 10 CSF and 3 brain), or noninflammatory CNS diseases inconsistent with MUO (11/22; 11 CSF and 2 brain) that served as negative controls. METHODS A case control study was performed by identifying MUO and non-MUO cases. Samples were blindly processed and then unblinded for comparative analyses. Inclusion criteria for MUO cases included consistent MRI lesions and inflammatory CSF with a negative PCR panel for infectious agents or histopathologic diagnosis. Dogs with glucocorticoid therapy within 2 weeks of sample collection were excluded. Fresh-frozen cerebrospinal fluid (CSF; 21) and brain (5) samples were collected and RNA and DNA were extracted separately for shotgun metagenomic sequencing. Known positive samples were used as controls to validate our sequencing and analysis pipelines and to establish limits of detection. Sequencing results were analyzed at a nucleotide and protein level for broad comparison to known infectious organisms. RESULTS No candidate etiologic agents were identified in dogs with MUO. CONCLUSIONS AND CLINICAL IMPORTANCE These results support but do not prove the hypothesis that MUO is not associated with infectious agents and might be an autoimmune disease.
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Affiliation(s)
- L L Hoon-Hanks
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO
| | - S McGrath
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO
| | - K L Tyler
- Department of Neurology, Medicine, and Immunology-Microbiology, University of Colorado School of Medicine, Aurora, CO
| | - C Owen
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO
| | - M D Stenglein
- Department of Microbiology, Immunology, and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO
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35
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Lequime S, Richard V, Cao-Lormeau VM, Lambrechts L. Full-genome dengue virus sequencing in mosquito saliva shows lack of convergent positive selection during transmission by Aedes aegypti. Virus Evol 2017; 3:vex031. [PMID: 29497564 PMCID: PMC5782851 DOI: 10.1093/ve/vex031] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Like other pathogens with high mutation and replication rates, within-host dengue virus
(DENV) populations evolve during infection of their main mosquito vector, Aedes
aegypti. Within-host DENV evolution during transmission provides opportunities
for adaptation and emergence of novel virus variants. Recent studies of DENV genetic
diversity failed to detect convergent evolution of adaptive mutations in mosquito tissues
such as midgut and salivary glands, suggesting that convergent positive selection is not a
major driver of within-host DENV evolution in the vector. However, it is unknown whether
this conclusion extends to the transmitted viral subpopulation because it is technically
difficult to sequence DENV genomes in mosquito saliva. Here, we achieved DENV full-genome
sequencing by pooling saliva samples collected non-sacrificially from 49 to 163 individual
Ae. aegypti mosquitoes previously infected with one of two DENV-1
genotypes. We compared the transmitted viral subpopulations found in the pooled saliva
samples collected in time series with the input viral population present in the infectious
blood meal. In all pooled saliva samples examined, the full-genome consensus sequence of
the input viral population was unchanged. Although the pooling strategy prevents analysis
of individual saliva samples, our results demonstrate the lack of strong convergent
positive selection during a single round of DENV transmission by Ae.
aegypti. This finding reinforces the idea that genetic drift and purifying
selection are the dominant evolutionary forces shaping within-host DENV genetic diversity
during transmission by mosquitoes.
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Affiliation(s)
- Sebastian Lequime
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, 28 rue du Docteur Roux, 75015 Paris, France.,Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, 25-28 rue du Docteur Roux, 75015 Paris, France.,Université Pierre et Marie Curie, Cellule Pasteur UPMC, 4 place Jussieu, 75005 Paris, France
| | - Vaea Richard
- Unit of Emerging Infectious Diseases, Institut Louis Malardé, BP 30, 98713 Papeete, Tahiti, French Polynesia
| | - Van-Mai Cao-Lormeau
- Unit of Emerging Infectious Diseases, Institut Louis Malardé, BP 30, 98713 Papeete, Tahiti, French Polynesia
| | - Louis Lambrechts
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, 28 rue du Docteur Roux, 75015 Paris, France.,Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, 25-28 rue du Docteur Roux, 75015 Paris, France
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36
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Promiscuous viruses-how do viruses survive multiple unrelated hosts? Curr Opin Virol 2017; 23:125-129. [PMID: 28577474 DOI: 10.1016/j.coviro.2017.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 12/24/2022]
Abstract
Arthropod-borne viruses (arboviruses) require efficient replication in taxonomically divergent hosts in order to perpetuate in nature. This review discusses recent advances in our understanding of the phylogenetic position of arthropod-borne viruses relative to insect-specific viruses, which appear to be more common and ecological requirements for successful adoption of the 'arbovirus phenotype.' Several molecular and other mechanisms that permit replication in divergent hosts are also discussed.
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37
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Grubaugh ND, Rückert C, Armstrong PM, Bransfield A, Anderson JF, Ebel GD, Brackney DE. Transmission bottlenecks and RNAi collectively influence tick-borne flavivirus evolution. Virus Evol 2016; 2:vew033. [PMID: 28058113 PMCID: PMC5210029 DOI: 10.1093/ve/vew033] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Arthropod-borne RNA viruses exist within hosts as heterogeneous populations of viral variants and, as a result, possess great genetic plasticity. Understanding the micro-evolutionary forces shaping these viruses can provide insights into how they emerge, adapt, and persist in new and changing ecological niches. While considerable attention has been directed toward studying the population dynamics of mosquito-borne viruses, little is known about tick-borne virus populations. Therefore, using a mouse and Ixodes scapularis tick transmission model, we examined Powassan virus (POWV; Flaviviridae, Flavivirus) populations in and between both the vertebrate host and arthropod vector. We found that genetic bottlenecks, RNAi-mediated diversification, and selective constraints collectively influence POWV evolution. Together, our data provide a mechanistic explanation for the slow, long-term evolutionary trends of POWV, and suggest that all arthropod-borne viruses encounter similar selective pressures at the molecular level (i.e. RNAi), yet evolve much differently due to their unique rates and modes of transmission.
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Affiliation(s)
- Nathan D Grubaugh
- Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA
| | - Claudia Rückert
- Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA
| | - Philip M Armstrong
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
| | - Angela Bransfield
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
| | - John F Anderson
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
| | - Gregory D Ebel
- Department of Microbiology Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Fort Collins, CO, USA
| | - Doug E Brackney
- The Connecticut Agricultural Experiment Station, Center for Vector Biology and Zoonotic Diseases, New Haven, CT, USA
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38
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Weger-Lucarelli J, Rückert C, Chotiwan N, Nguyen C, Garcia Luna SM, Fauver JR, Foy BD, Perera R, Black WC, Kading RC, Ebel GD. Vector Competence of American Mosquitoes for Three Strains of Zika Virus. PLoS Negl Trop Dis 2016; 10:e0005101. [PMID: 27783679 PMCID: PMC5081193 DOI: 10.1371/journal.pntd.0005101] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Accepted: 10/09/2016] [Indexed: 11/18/2022] Open
Abstract
In 2015, Zika virus (ZIKV; Flaviviridae; Flavivirus) emerged in the Americas, causing millions of infections in dozens of countries. The rapid spread of the virus and the association with disease outcomes such as Guillain-Barré syndrome and microcephaly make understanding transmission dynamics essential. Currently, there are no reports of vector competence (VC) of American mosquitoes for ZIKV isolates from the Americas. Further, it is not clear whether ZIKV strains from other genetic lineages can be transmitted by American Aedes aegypti populations, and whether the scope of the current epidemic is in part facilitated by viral factors such as enhanced replicative fitness or increased vector competence. Therefore, we characterized replication of three ZIKV strains, one from each of the three phylogenetic clades in several cell lines and assessed their abilities to be transmitted by Ae. aegypti mosquitoes. Additionally, laboratory colonies of different Culex spp. were infected with an American outbreak strain of ZIKV to assess VC. Replication rates were variable and depended on virus strain, cell line and MOI. African strains used in this study outcompeted the American strain in vitro in both mammalian and mosquito cell culture. West and East African strains of ZIKV tested here were more efficiently transmitted by Ae. aegypti from Mexico than was the currently circulating American strain of the Asian lineage. Long-established laboratory colonies of Culex mosquitoes were not efficient ZIKV vectors. These data demonstrate the capacity for additional ZIKV strains to infect and replicate in American Aedes mosquitoes and suggest that neither enhanced virus replicative fitness nor virus adaptation to local vector mosquitoes seems likely to explain the extent and intensity of ZIKV transmission in the Americas. The mechanisms contributing to the explosive nature of the current ZIKV outbreak in the Americas are poorly understood. Therefore, we characterized the replication of three strains, one from each phylogenetic clade of ZIKV and evaluated virus strain differences in transmission efficiency by American mosquitoes. Our results suggest that the strain currently circulating in the Americas does not have unusually high infectivity for American Ae. aegypti as compared to the African strains used in this study. Colonized Culex mosquitoes were inefficient vectors. In vitro data suggested slower replication and decreased fitness for the currently circulating American strain compared to African strains isolated decades ago. Therefore, viral adaptation to local mosquitoes does not appear, at present, to be driving the current ZIKV outbreak in the Americas.
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Affiliation(s)
- James Weger-Lucarelli
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Claudia Rückert
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Nunya Chotiwan
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Chilinh Nguyen
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Selene M. Garcia Luna
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Joseph R. Fauver
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Brian D. Foy
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Rushika Perera
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - William C. Black
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Rebekah C. Kading
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
| | - Gregory D. Ebel
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado
- * E-mail:
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39
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Dynamics of West Nile virus evolution in mosquito vectors. Curr Opin Virol 2016; 21:132-138. [PMID: 27788400 DOI: 10.1016/j.coviro.2016.09.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 09/09/2016] [Accepted: 09/12/2016] [Indexed: 01/24/2023]
Abstract
West Nile virus remains the most common cause of arboviral encephalitis in North America. Since it was introduced, it has undergone adaptive genetic change as it spread throughout the continent. The WNV transmission cycle is relatively tractable in the laboratory. Thus the virus serves as a convenient model system for studying the population biology of mosquito-borne flaviviruses as they undergo transmission to and from mosquitoes and vertebrates. This review summarizes the current knowledge regarding the population dynamics of this virus within mosquito vectors.
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40
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Transmission and evolution of tick-borne viruses. Curr Opin Virol 2016; 21:67-74. [PMID: 27569396 DOI: 10.1016/j.coviro.2016.08.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 08/08/2016] [Accepted: 08/09/2016] [Indexed: 02/05/2023]
Abstract
Ticks transmit a diverse array of viruses such as tick-borne encephalitis virus, Powassan virus, and Crimean-Congo hemorrhagic fever virus that are reemerging in many parts of the world. Most tick-borne viruses (TBVs) are RNA viruses that replicate using error-prone polymerases and produce genetically diverse viral populations that facilitate their rapid evolution and adaptation to novel environments. This article reviews the mechanisms of virus transmission by tick vectors, the molecular evolution of TBVs circulating in nature, and the processes shaping viral diversity within hosts to better understand how these viruses may become public health threats. In addition, remaining questions and future directions for research are discussed.
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41
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Measurements of Intrahost Viral Diversity Are Extremely Sensitive to Systematic Errors in Variant Calling. J Virol 2016; 90:6884-95. [PMID: 27194763 DOI: 10.1128/jvi.00667-16] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Accepted: 05/11/2016] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED With next-generation sequencing technologies, it is now feasible to efficiently sequence patient-derived virus populations at a depth of coverage sufficient to detect rare variants. However, each sequencing platform has characteristic error profiles, and sample collection, target amplification, and library preparation are additional processes whereby errors are introduced and propagated. Many studies account for these errors by using ad hoc quality thresholds and/or previously published statistical algorithms. Despite common usage, the majority of these approaches have not been validated under conditions that characterize many studies of intrahost diversity. Here, we use defined populations of influenza virus to mimic the diversity and titer typically found in patient-derived samples. We identified single-nucleotide variants using two commonly employed variant callers, DeepSNV and LoFreq. We found that the accuracy of these variant callers was lower than expected and exquisitely sensitive to the input titer. Small reductions in specificity had a significant impact on the number of minority variants identified and subsequent measures of diversity. We were able to increase the specificity of DeepSNV to >99.95% by applying an empirically validated set of quality thresholds. When applied to a set of influenza virus samples from a household-based cohort study, these changes resulted in a 10-fold reduction in measurements of viral diversity. We have made our sequence data and analysis code available so that others may improve on our work and use our data set to benchmark their own bioinformatics pipelines. Our work demonstrates that inadequate quality control and validation can lead to significant overestimation of intrahost diversity. IMPORTANCE Advances in sequencing technology have made it feasible to sequence patient-derived viral samples at a level sufficient for detection of rare mutations. These high-throughput, cost-effective methods are revolutionizing the study of within-host viral diversity. However, the techniques are error prone, and the methods commonly used to control for these errors have not been validated under the conditions that characterize patient-derived samples. Here, we show that these conditions affect measurements of viral diversity. We found that the accuracy of previously benchmarked analysis pipelines was greatly reduced under patient-derived conditions. By carefully validating our sequencing analysis using known control samples, we were able to identify biases in our method and to improve our accuracy to acceptable levels. Application of our modified pipeline to a set of influenza virus samples from a cohort study provided a realistic picture of intrahost diversity and suggested the need for rigorous quality control in such studies.
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42
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Lequime S, Fontaine A, Ar Gouilh M, Moltini-Conclois I, Lambrechts L. Genetic Drift, Purifying Selection and Vector Genotype Shape Dengue Virus Intra-host Genetic Diversity in Mosquitoes. PLoS Genet 2016; 12:e1006111. [PMID: 27304978 PMCID: PMC4909269 DOI: 10.1371/journal.pgen.1006111] [Citation(s) in RCA: 97] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Accepted: 05/17/2016] [Indexed: 01/15/2023] Open
Abstract
Due to their error-prone replication, RNA viruses typically exist as a diverse population of closely related genomes, which is considered critical for their fitness and adaptive potential. Intra-host demographic fluctuations that stochastically reduce the effective size of viral populations are a challenge to maintaining genetic diversity during systemic host infection. Arthropod-borne viruses (arboviruses) traverse several anatomical barriers during infection of their arthropod vectors that are believed to impose population bottlenecks. These anatomical barriers have been associated with both maintenance of arboviral genetic diversity and alteration of the variant repertoire. Whether these patterns result from stochastic sampling (genetic drift) rather than natural selection, and/or from the influence of vector genetic heterogeneity has not been elucidated. Here, we used deep sequencing of full-length viral genomes to monitor the intra-host evolution of a wild-type dengue virus isolate during infection of several mosquito genetic backgrounds. We estimated a bottleneck size ranging from 5 to 42 founding viral genomes at initial midgut infection, irrespective of mosquito genotype, resulting in stochastic reshuffling of the variant repertoire. The observed level of genetic diversity increased following initial midgut infection but significantly differed between mosquito genetic backgrounds despite a similar initial bottleneck size. Natural selection was predominantly negative (purifying) during viral population expansion. Taken together, our results indicate that dengue virus intra-host genetic diversity in the mosquito vector is shaped by genetic drift and purifying selection, and point to a novel role for vector genetic factors in the genetic breadth of virus populations during infection. Identifying the evolutionary forces acting on arboviral populations within their arthropod vector provides novel insights into arbovirus evolution. During infection of their arthropod vectors, arthropod-borne viruses (arboviruses) such as dengue viruses traverse several anatomical barriers that are believed to cause dramatic reductions in population size. Such population bottlenecks challenge the maintenance of viral genetic diversity, which is considered critical for fitness and adaptability of arboviruses. Anatomical barriers in the vector were previously associated with both maintenance of arboviral genetic diversity and alteration of the variant repertoire. However, the relative role of random processes and natural selection, and the influence of vector genetic heterogeneity have not been elucidated. In this study, we used high-throughput sequencing to monitor dengue virus genetic diversity during infection of several genetic backgrounds of their mosquito vector. Our results show that initial infection of the vector is randomly founded by only a few tens of individual virus genomes. The overall level of viral genetic diversity generated during infection was predominantly under purifying selection but differed significantly between mosquito genetic backgrounds. Thus, in addition to random evolutionary forces and the purging of deleterious mutations that shape dengue virus genetic diversity during vector infection, our results also point to a novel role for vector genetic factors in the genetic breadth of virus populations.
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Affiliation(s)
- Sebastian Lequime
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
- Université Pierre et Marie Curie, Cellule Pasteur UPMC, Paris, France
- * E-mail: (SL); (LL)
| | - Albin Fontaine
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
- Equipe Résidente de Recherche d’Infectiologie Tropicale, Division Expertise, Institut de Recherche Biomédicale des Armées, Brétigny-sur-Orge, France
| | - Meriadeg Ar Gouilh
- Unité Environnement et Risques Infectieux, Cellule d’Intervention Biologique d’Urgence, Department of Infection and Epidemiology, Institut Pasteur, Paris, France
- EA4655, Unité Risques Microbiens U2RM, Université de Caen Normandie, Caen, France
| | - Isabelle Moltini-Conclois
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
| | - Louis Lambrechts
- Insect-Virus Interactions Group, Department of Genomes and Genetics, Institut Pasteur, Paris, France
- Centre National de la Recherche Scientifique, Unité de Recherche Associée 3012, Paris, France
- * E-mail: (SL); (LL)
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43
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Coffey LL, Reisen WK. West Nile Virus Fitness Costs in Different Mosquito Species. Trends Microbiol 2016; 24:429-430. [PMID: 27108207 DOI: 10.1016/j.tim.2016.04.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 04/12/2016] [Indexed: 11/25/2022]
Abstract
West Nile virus (WNV) remains an important public health problem causing annual epidemics in the United States. Grubaugh et al. observed that WNV genetic divergence is dependent on the vector mosquito species. This suggests that specific WNV vector-bird species pairings may generate novel genotypes that could promote outbreaks.
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Affiliation(s)
- Lark L Coffey
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
| | - William K Reisen
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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44
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Grubaugh ND, Weger-Lucarelli J, Murrieta RA, Fauver JR, Garcia-Luna SM, Prasad AN, Black WC, Ebel GD. Genetic Drift during Systemic Arbovirus Infection of Mosquito Vectors Leads to Decreased Relative Fitness during Host Switching. Cell Host Microbe 2016; 19:481-92. [PMID: 27049584 DOI: 10.1016/j.chom.2016.03.002] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/19/2016] [Accepted: 03/07/2016] [Indexed: 11/30/2022]
Abstract
The emergence of mosquito-borne RNA viruses, such as West Nile virus (WNV), is facilitated by genetically complex virus populations within hosts. Here, we determine whether WNV enzootic (Culex tarsalis, Cx. quinquefasciatus, and Cx. pipiens) and bridge vectors (Aedes aegypti) have differential impacts on viral mutational diversity and fitness. During systemic mosquito infection, WNV faced stochastic reductions in genetic diversity that rapidly was recovered during intra-tissue population expansions. Interestingly, this intrahost selection and diversification was mosquito species dependent with Cx. tarsalis and Cx. quinquefasciatus exhibiting greater WNV divergence. However, recovered viral populations contained a preponderance of potentially deleterious mutations (i.e., high mutational load) and had lower relative fitness in avian cells compared to input virus. These findings demonstrate that the adaptive potential associated with mosquito transmission varies depending on the mosquito species and carries a significant fitness cost in vertebrates.
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Affiliation(s)
- Nathan D Grubaugh
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - James Weger-Lucarelli
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Reyes A Murrieta
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Joseph R Fauver
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Selene M Garcia-Luna
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Abhishek N Prasad
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - William C Black
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA
| | - Gregory D Ebel
- Department of Microbiology, Immunology and Pathology, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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Misencik MJ, Grubaugh ND, Andreadis TG, Ebel GD, Armstrong PM. Isolation of a Novel Insect-Specific Flavivirus from Culiseta melanura in the Northeastern United States. Vector Borne Zoonotic Dis 2016; 16:181-90. [PMID: 26807512 DOI: 10.1089/vbz.2015.1889] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The genus Flavivirus includes a number of newly recognized viruses that infect and replicate only within mosquitoes. To determine whether insect-specific flaviviruses (ISFs) may infect Culiseta (Cs.) melanura mosquitoes, we screened pools of field-collected mosquitoes for virus infection by RT-PCR targeting conserved regions of the NS5 gene. NS5 nucleotide sequences amplified from Cs. melanura pools were genetically similar to other ISFs and most closely matched Calbertado virus from Culex tarsalis, sharing 68.7% nucleotide and 76.1% amino acid sequence identity. The complete genome of one virus isolate was sequenced to reveal a primary open reading frame (ORF) encoding a viral polyprotein characteristic of the genus Flavivirus. Phylogenetic analysis showed that this virus represents a distinct evolutionary lineage that belongs to the classical ISF group. The virus was detected solely in Cs. melanura pools, occurred in sampled populations from Connecticut, New York, New Hampshire, and Maine, and infected both adult and larval stages of the mosquito. Maximum likelihood estimate infection rates (MLE-IR) were relatively stable in overwintering Cs. melanura larvae collected monthly from November of 2012 through May of 2013 (MLE-IR = 0.7-2.1/100 mosquitoes) and in host-seeking females collected weekly from June through October of 2013 (MLE-IR = 3.8-11.5/100 mosquitoes). Phylogenetic analysis of viral sequences revealed limited genetic variation that lacked obvious geographic structure among strains in the northeastern United States. This new virus is provisionally named Culiseta flavivirus on the basis of its host association with Cs. melanura.
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Affiliation(s)
- Michael J Misencik
- 1 Center for Vector Biology and Zoonotic Diseases , The Connecticut Agricultural Experiment Station, New Haven, Connecticut
| | - Nathan D Grubaugh
- 2 Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University , Fort Collins, Colorado
| | - Theodore G Andreadis
- 1 Center for Vector Biology and Zoonotic Diseases , The Connecticut Agricultural Experiment Station, New Haven, Connecticut
| | - Gregory D Ebel
- 2 Arthropod-Borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology, and Pathology, Colorado State University , Fort Collins, Colorado
| | - Philip M Armstrong
- 1 Center for Vector Biology and Zoonotic Diseases , The Connecticut Agricultural Experiment Station, New Haven, Connecticut
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Grubaugh ND, Massey A, Shives KD, Stenglein MD, Ebel GD, Beckham JD. West Nile Virus Population Structure, Injury, and Interferon-Stimulated Gene Expression in the Brain From a Fatal Case of Encephalitis. Open Forum Infect Dis 2015; 3:ofv182. [PMID: 26730392 PMCID: PMC4697916 DOI: 10.1093/ofid/ofv182] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 11/10/2015] [Indexed: 11/24/2022] Open
Abstract
Background. West Nile virus (WNV) infection in humans can result in severe, acute encephalitis typically involving subcortical gray matter brain regions. West Nile virus replication within specific human brain regions from a human case of acute encephalitis has not been studied. Methods. We describe a fatal case of WNV encephalitis in which we obtained tissue from specific brain regions at autopsy to evaluate viral-host interactions using next-generation sequencing and immunohistochemistry analysis. Results. We found that WNV populations in the injured subcortical brain regions exhibited increased amino acid variation and increased expression of specific interferon genes compared with cortical tissues despite similar viral burden. Conclusions. These observational, patient-based data suggest that neuronal injury and the strength of viral selection pressure may be associated with the level of the innate immune responses. Further studies in human and animal models evaluating the role of innate immune responses on injury patterns and viral selection pressure are needed.
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Affiliation(s)
- Nathan D Grubaugh
- Department of Microbiology Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins
| | - Aaron Massey
- Departments of Medicine and Neurology, Division of Infectious Diseases , University of Colorado School of Medicine
| | - Katherine D Shives
- Department of Immunology and Microbiology , University of Colorado Anschutz Medical Campus , Aurora
| | - Mark D Stenglein
- Department of Microbiology Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins
| | - Gregory D Ebel
- Department of Microbiology Immunology and Pathology , College of Veterinary Medicine and Biomedical Sciences, Colorado State University , Fort Collins
| | - J David Beckham
- Departments of Medicine and Neurology, Division of Infectious Diseases, University of Colorado School of Medicine; Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora
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Dridi M, Rosseel T, Orton R, Johnson P, Lecollinet S, Muylkens B, Lambrecht B, Van Borm S. Next-generation sequencing shows West Nile virus quasispecies diversification after a single passage in a carrion crow (Corvus corone) in vivo infection model. J Gen Virol 2015; 96:2999-3009. [PMID: 26297666 DOI: 10.1099/jgv.0.000231] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
West Nile virus (WNV) occurs as a population of genetic variants (quasispecies) infecting a single animal. Previous low-resolution viral genetic diversity estimates in sampled wild birds and mosquitoes, and in multiple-passage adaptation studies in vivo or in cell culture, suggest that WNV genetic diversification is mostly limited to the mosquito vector. This study investigated genetic diversification of WNV in avian hosts during a single passage using next-generation sequencing. Wild-captured carrion crows were subcutaneously infected using a clonal Middle-East WNV. Blood samples were collected 2 and 4 days post-infection. A reverse-transcription (RT)-PCR approach was used to amplify the WNV genome directly from serum samples prior to next-generation sequencing resulting in an average depth of at least 700 × in each sample. Appropriate controls were sequenced to discriminate biologically relevant low-frequency variants from experimentally introduced errors. The WNV populations in the wild crows showed significant diversification away from the inoculum virus quasispecies structure. By contrast, WNV populations in intracerebrally infected day-old chickens did not diversify from that of the inoculum. Where previous studies concluded that WNV genetic diversification is only experimentally demonstrated in its permissive insect vector species, we have experimentally shown significant diversification of WNV populations in a wild bird reservoir species.
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Affiliation(s)
- M Dridi
- Operational Direction of Viral Diseases, Veterinary and Agrochemical Research Center (CODA-CERVA-VAR), 99 Groeselenberg, 1180 Brussels, Belgium
| | - T Rosseel
- Operational Direction of Viral Diseases, Veterinary and Agrochemical Research Center (CODA-CERVA-VAR), 99 Groeselenberg, 1180 Brussels, Belgium
| | - R Orton
- Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
- MRC-University of Glasgow Centre for Virus Research, Institute of Infection Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - P Johnson
- Boyd Orr Centre for Population and Ecosystem Health, Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - S Lecollinet
- UMR1161 Virologie INRA, ANSES, ENVA, French Agency for Food, Environmental and Occupational Health & Safety (Anses), 23 avenue du Général De Gaulle, 94706 Maisons-Alfort, France
| | - B Muylkens
- Integrated Veterinary Research Unit, University of Namur, 61 rue de Bruxelles, 5000 Namur, Belgium
| | - B Lambrecht
- Operational Direction of Viral Diseases, Veterinary and Agrochemical Research Center (CODA-CERVA-VAR), 99 Groeselenberg, 1180 Brussels, Belgium
| | - S Van Borm
- Operational Direction of Viral Diseases, Veterinary and Agrochemical Research Center (CODA-CERVA-VAR), 99 Groeselenberg, 1180 Brussels, Belgium
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